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> Too hot of a plug?
DNHunt
post May 21 2003, 06:00 PM
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I run an MSD 6A ignition and I have been using Bosch W5CC plugs with a .050 gap. This time I couldn't find that plug so we substituted an NGK R5671A-7 with the same gap. I ran it for about 20 miles and the car runs great. Cylinder head temperatures are the same but when I checked the plugs they sure are lighter in color than I am used to. How long does it take to get an idea of the way the spark plug burns? Do I need more miles or is this plug hotter?

Thanks for your help,
Dave
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Brad Roberts
post May 21 2003, 06:33 PM
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That plug is hotter. It should only take a few minutes.

We typically run a W7DC in all of our cars (street and track)


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seanery
post May 21 2003, 06:40 PM
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That's what we just put in my car, right?
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Brad Roberts
post May 21 2003, 06:44 PM
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Correct.


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DNHunt
post May 21 2003, 07:53 PM
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Should I be worried? Here is a picture of the two plugs out of #1. The Bosch is on the right and the NGK is on the left. Granted the Bosch is old but it doesn't look as bad as the picture. It has dark grey electrodes and some soot at the outer ring. It was in the car when I converted to the Megasquirt ECU and saw some rich mixtures averaging around 12.5/1.

The NGK is certainly seeing leaner conditions with the system now running in closed loop correcting to 13.8/1 for a target AFR.

Thanks,
Dave
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DNHunt
post May 21 2003, 08:13 PM
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Sorry forgot the picture, doh!!


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seanery
post May 21 2003, 08:15 PM
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I'm surprised by the difference in the size of the plug north of the threads. The NGK is much smaller (skinnier) than the Bosch.
Does that affect performance?
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DNHunt
post May 21 2003, 08:24 PM
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That's kind of misleading. Everything looks the same to me except the size of the hex on the Bosch is 13/16 and the NGK is 5/8. Also, the NGK sports a v groove in the electrode which they have all over their box. Gimmick?

Dave
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Brad Roberts
post May 22 2003, 12:48 AM
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The NGK looks lean to me. The V groove works.. not sure what we gain.. but we tested some AC Delco's with the groove and they showed better flame propagation than a non grooved plug.

Hum.. the Bosch is/was toast. I'm surprised it ran on all 4 cyl's.

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Scott S
post May 22 2003, 09:51 AM
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Hi Brad -
What are you gapping your plugs at? I am getting ready to change my plugs and can't find the MSD paperwork (you know, that paper I made sure to put in a place where I wouldn't lose it!?)

I am using the 6AL, with a comp-u-fire and the stock 2.0 distributer with the vaccum hooked up to the passenger side 40 Weber.

Thanks!
Scott S
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DNHunt
post May 22 2003, 11:08 AM
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Guess I'll richen the mix just a little. I was trying to get it as lean as I could, but with the hotter plug I may be too lean. The software with the megasquirt allows you to richen or lean the whole fuel table by a changing a fueling constant they call Reg Fuel.
I'll try a few percent and see what it looks like.

Dave
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Brad Roberts
post May 22 2003, 11:08 AM
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45 thou.

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Bleyseng
post May 22 2003, 11:40 AM
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How about this one, Brad?

Geoff
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Bleyseng
post May 22 2003, 11:41 AM
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G*d D**m buttons


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seanery
post May 22 2003, 11:55 AM
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Scotch tape dispenser with a spark plug!

What the F$&^!!!!
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Bleyseng
post May 22 2003, 12:05 PM
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That was so I could take a picture of it ya nitwit! Atleast I don't have my effin' shoes in the picture!
Geoff
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Brad Roberts
post May 22 2003, 12:16 PM
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It looks pretty damn good to me. A tad lean.. but no reason to change anything. What I dont want to see: WHITE. Tan with a light grey = good.


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seanery
post May 22 2003, 12:26 PM
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What?
Did I post something with my feet in the pic?
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Bleyseng
post May 22 2003, 01:56 PM
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Sean, that's a standing joke on the BBS's. People take pictures of parts and always have their feet in the shot. duh!
Geoff
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Anton
post May 22 2003, 02:51 PM
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Geoff,

what spark kind of plug is that in the picture? Looks like the one I use in my VW Golf 1.8i, the Bosch N7BYC, and NOT a 914 (type 4 engine) plug.

Please tell me if such a multiple electrode plug can be used in a 914 (with standard ignition). Why else did you show the picture?

The spark is directed differently with such a multiple electrode plug, so combustion is more uniform. On the other hand, it would not surprise me if this only works with electronic spark units (MSD or whatever).

Anton
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